Hi!
We are plunning to replace our single node installation with moodle cluster: load balancer, several Application servers (2 for now), cache server and db server (also a cluster in future).
Moodle documentation gives moderate overview on how to do it.
As far as I understand, there is no way to organize A/B testing with several Moodle servers (to give new plugins, themes, versions to some part of users) because all cluster nodes should be identical and a lot of information about configuration stored in DB.
So is there any chance to organize A/B testing or not?